//构造函数, 类的一部分,
var Book = function(isbn, title, author) {  //函数表达式
    this.isbn = 'isbn';
    this.title = 'title';
    this.author = 'author';
}
Book.prototype = {
    checkIsbn: function() {},
    borrow: function() {
        console.log('Book的')
    },
}
//血缘关系
var xhs = new Book('978-7-115-19128-1/TP', '你不知道的JavaScript', 'KYLE');
xhs.borrow();
//空对象
var sjms = {};
Book.call(sjms, '986-444', '葵花宝典', '金庸');
sjms.__proto__ = Book.prototype;
// sjms.borrow();
console.log(sjms.__proto__);
console.log(Book.prototype.__proto__);
sjms.borrow();
console.log(sjms.toString());